Biocompatible evaluation of magnesium-containing MAO coating developed on Ti6Al4V alloy

Abstract

Event Abstract Back to Event Biocompatible evaluation of magnesium-containing MAO coating developed on Ti6Al4V alloy Ying Zhao1* and Rongfa Zhang2* 1 Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Center for Human Tissues and Organs Degeneration, China 2 Jiangxi Science and Technology Normal University, Jiangxi Key Laboratory of Surface Engineering, China Introduction: Micro-arc oxidation (MAO) is an important surface modification technology, which can produce porous, relatively rough and firmly adherent oxide ceramic coatings on the titanium alloy surface. According to the structure of natural bone tissue with organic and inorganic components, in this study we design a biocompatible magnesium-containing composite coating, which is formed via MAO in the electrolyte containing phytic acid and EDTA-MgNa. Methods: The Ti6Al4V samples were anodized at 50mA/cm2 in an aqueous solution containing 15 g/l phytic acid and different concentrations of EDTA-MgNa (5 g/l, 10 g/l, 15 g/l, 20 g/l) (denoted as S5, S10, S15, S20). MC3T3-E1 preosteoblasts were cultured on various sample surfaces to examine cytocompatibility. Results and Discussion: Fig.1 shows surface morphology of MAO coatings formed in different concentrations of EDTA-MgNa. As shown, the S5 (Fig. 1b) and S10 (Fig. 1c) samples display porous structure with the pore size from 0.1 to 2.0 μm, in comparison the S15 (Fig. 1d) and S20 (Fig. 1e) samples reveal more homogeneous porous structure with the pore size from 1.0 to 3.0 μm. Mg content of the oxide film is gradually increased with the enhancement of EDTA-MgNa concentration in electrolyte (Fig. 1f). It illustrate that the EDTA-MgNa concentration can regulate the surface composition, morphology as well as the pore size of the titanium oxide film. High concentration of EDTA-MgNa is favorable to increase pore size and Mg content of oxide film. Fig. 2 reveals preosteoblasts proliferation and differentiation on various MAO samples. Gradual increases in the cell proliferations are observed on all sample surfaces throughout the culturing period (Fig. 2a). In particular, S15 sample show the highest cell proliferation on day1 while sample S5 show the highest cell proliferation on days 3 and 7compared with other treated samples. In addition, significant increased ALP activity levels can be observed on S5 and S15 after 14 and 21 days of culture (Fig. 2b). Generally, S15 and S5 samples present better cell proliferation and differentiation than other samples, whereas S20 sample shows the worst cytocompatibility. Our data indicate minute amount magnesium ions effectively promote preosteoblasts proliferation and differentiation, but when magnesium ion content in the MAO coatings increase to around 2.3wt%, negative effect on cytocompatibility occur. Conclusions: Magnesium-containing biocompatible ceramic coatings can be formed on Ti6Al4V alloy via MAO. High concentration of EDTA-MgNa in the electroly is favorable to increase pore size and Mg content of oxide film. Minute amount Mg in the oxide film effectively promotes preosteoblasts proliferation and differentiation, but negative effect on cytocompatibility is produced when Mg content is increased to 2.3wt%. Our study suggests biocompatible magnesium-containing titanium alloys have attractive potential as orthopedic implants. National Natural Science Foundation of China (81572113, 51501218, 51361011); Guangdong Provincial Science and technology projects (2014A010105033); Shenzhen Peacock Programs KQCX20140521115045444 and 110811003586331